Producing and mounting crowns screwed onto watch cases are well known.
However, for aesthetic reasons, it is preferable, if the external face of the external part of the crown features a distinctive sign, to be able to guarantee that the distinctive sign is located in a particular angular orientation relative to the longitudinal axis of the tube of the watch case to which the crown is screwed. Otherwise the angular position of the distinctive sign is random.
The published patent application EP 2 182 417 describes a screw crown composed of a cap, three distinct tubes and a locknut.
The first tube is connected to the crown and is screwed onto the second tube, the third tube is adapted to receive the second tube, and the second tube and the third tube include indexing elements.
The third tube includes internal teeth provided on the interior perimeter and arranged to cooperate with a toothed ring of the second tube. The second tube and the third tube are locked in translation by a ring and form a subassembly having an orientable external thread onto which the crown associated with the first tube is screwed.
The angular orientation is fixed once and for all and is linked directly to the number of teeth present on the second tube and the third tube, and the number of indexing positions is necessarily limited because of the small diameters of these tubes. Moreover, this solution necessitates three tubes and is difficult to fit.
Moreover, there is the risk of the crown and the tubes becoming detached from the watch case if too high a torque is applied to the crown.
The drawbacks of this crown have been overcome by the solution proposed in international application PCT/CH2011/000094 filed 28 Apr. 2011 and published with the number WO2011137544 after the present patent application was filed. The subject matter of this international application is a watch case comprising a control crown composed of two parts, namely an internal part and an external part, this latter part having to be retained in the internal part by a clamping ring.